[Kdenlive-devel] ffmpeg screen capture with Alsa sound ?

[Dan Dennedy]

On Tue, Oct 21, 2008 at 12:18 PM, Jean-Michel Pouré <jm at poure.com> wrote:
> Le mardi 21 octobre 2008 à 21:13 +0200, Jean-Michel Pouré a écrit :
>> Now, how to capture sound from Alsa input?

Well, ffmpeg only supports OSS. Maybe all that is required is the ALSA
OSS emulation, but your mileage may vary

>> I know that I could record seperately, but I fear unsynchronized
>> sound.
>
> This seems to be possible using Sox:
> http://develcuy.com/en/content/debian/howto-screencasting-console-sox-and-ffmpeg
>
> Example:
> sox -t alsa "hw:0,0" -t ogg -A -2 -c1 -r11025 - | ffmpeg -y -i - -ar
> 11025 -ab 52 -ac 1 -f x11grab -s 800x600 -i :0.0+10,20 -b 200 -r 12
> -aspect 4:3 -f flv test.flv

This seems rather silly. First, why use sox and not arecord? Secondly,
the audio is encoded twice when it could pass uncompressed pcm through
the pipe:

arecord -D default -t raw -c 1 -f S16_LE -r 11025 | ffmpeg -f s16le
-ar 11025 -ac 1 -i - ...

-- 
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